"desktop" is not a model number, it's only a term that can apply to thousands of computers, each requiring a unique set of drivers. I'm afraid I cannot help based on your vague hardware description. Last time I checked, Matsonic WAS a motherboard manufacturer, not a desktop maker. I say "WAS" because they're no longer in business.

To find make and model of pc hardware, EVEREST Home Edition is a free system diagnostics, system information program that will id most hardware on-board a mb. as well as the actual motherboard. It will, in some cases, actually provide a download link for the driver.